The Firestone Affinity tires on the 16" rims take 30 PSI cold/34 PSI hot. I usually run mine 1 or 2 PSI over the recommendation.

Another thing to keep in mind is that the Firestone Affinity tires (at least the ones I had on my Malibu's) are not great tires to begin with and the centres tend wear out fast if overinflated.

However, the Firestone Affinity tires on my HHR look nothing like the ones that were on our Malibu's.